A known problem with rolling-element bearings (especially those that operate at high speeds but at low loads) is skidding. The rolling element, instead of rolling on the inner track of the bearing, slides along it. This causes the rolling element to heat up at the contact point. If the sliding element breaks through the lubricant film, damage may be caused to the rolling elements or to the tracks. This phenomenon is known as skidding.
A known way to reduce skidding in lightly-loaded bearings is deliberately to make the outer race non-circular so that an interference exists across the bearing at two or more points. In use, the outer race will then bend due to this interference until a force equilibrium is reached, and a resultant load will be present at two or more positions across the bearing. The magnitude of the force can be controlled (by suitable choice of the magnitude of the non-circularity) to prevent the bearing from skidding.
A disadvantage with such bearings is that they require a squeeze film housing, or some other type of housing with enough clearance to allow the outer race to bend. If it is not possible to incorporate such a housing (for example, because of space or weight restrictions or oil feed issues) then it will be necessary to use a clear housing or a flanged outer race. In high speed applications a clear housing may be prone to fretting and so a flanged outer race is preferable. Another reason that a flanged outer race may be preferred is that such a race allows tighter control of the alignment of the shaft carried by the bearing.
A problem is that a flanged outer race is usually much stiffer than other types of outer race. The solution to the problem of skidding set out above, using a non-circular outer race, relies on the flexibility of the outer race and consequently it is unsatisfactory to use a flanged outer race in this situation.